Carburetor



Jan. 30, 1934. w, c ARTER 1,945,180

CARBURETOR Filed Oct. 30. 1931 3 Sheets-Sheet l 9 3 s i 5 1 kg 5' Mwwrae L 12/ A WILL/HM 6. C/MTMQ a; 5r

y 8, 1934- c. L. BRACKETT 1,958,180

COUPLING MECHANISM FOR WASHERS AND HEADED FASTENERS Original Filed Feb. 21, 1931 3 Sheets-Sheet 2 Jan. 30, 1934. w. c. CARTER 1,945,180

CARBURETOR Filed Oct. 30. 1931 3 Sheets-Sheet 3 ,qmnnnnnnn 'i //Vl 6I-/TOE: WILL/HM C. CARTER Patented Jan. 30, 1934 UNITED STATES- PATENT OFFICE 15 Claims.

This invention relates to carburetors for internal combustion engines and is applicable to down-draft and up-draft carburetors.

One object of my invention is to provide a carburetor for internal combustion engines that is equipped with an idle stabilizer which effectively eliminates the possibility of the engine stopping accidentally when it is idling, due to failure on the part of the operator to manually open the throttle valve of the carburetor when the engine misses or fires unevenly, and thus causes the suction in the intake to drop to such an extent or degree that it will not draw sufiicient combustible mixture past the edge of the throttle valve to maintain the engine in operation.

Another object is to provide a carburetor that is equipped with an automatic choke relief of novel construction for preventing theengine from stalling or stopping, due to failure on the part of the operator to release or restore the choking mechanism to its normal position, after the engine has started firing.

Another object is to provide a carburetor that is equipped with a novel means for destroying or breaking a siphon that is used to supply liquid fuel to the main passageway of the carburetor under certain operating conditions.

Another object is to provide a carburetor in which the idle stabilizer previously referred to also actsas a throttling by-pass around the throttle valve and as a means for automatically increasing the ratio of fuel to air under certain operating conditions.

And still another object is to provide a carburetor that is equipped with a novel means for producing or supplying an accelerating charge to the intake of the engine. Other objects and desirable features of my invention will be hereinafter pointed out.'

40 Figure 1 of the drawings is a vertical transverse sectional view of my improved carburetor, taken on the line 1-1 of Figure 2.

Figure 2 is a top plan view of the carburetor, with the flame arrester removed.

Figure 3 is a vertical transverse sectional view, taken on the line 3-3 of Figure 2.

Figure 4 is an enlarged, vertical sectional view, taken on the line 44 of Figure 2, looking in the direction indicated by the arrows.

Figure 5 is a detail view, showing the cam and arm on the throttle valve shaft that form part of the mechanism for varying the air supply and the liquid fuel supply.

Figure 6 is a perspective view of the air admission valve.

Main elements or parts of carburetor I have herein illustrated my invention embodied in a down-draft carburetor, but, as previously explained, the invention is applicable to updraft carburetors. The carburetor is so designed that it has two separate and distinct fuel ranges,

i. e., a power range in which the proportion or ratio of fuel to air is relatively high and great enough to produce adequate power for a heavy load, and an economy range in which the ratio or proportion of fuel to air is considerably lower, but is great enough to take care of the requirements at idle speeds or when the engine is operating under a normal load or maximum load. When the engine is operating under a heavy load 30 with a wide open throttle, the power range prevails and the carburetor acts as a plain tube carburetor whose fuel ratio is high enough to produce great power, and when the engine is idling or operating under a normal load with the throttle valve in an intermediate position or nearly closed, the economy range prevails and the carburetor acts as a mechanical carburetor whose fuel ratio is considerably lower than the fuel ratio which prevails when the carburetor is acting as a plain tube carburetor. Under cer-- tain conditions,.when the carburetor is acting as a ,mechanical carburetor, a means becomes operative to automatically change the fuel ratio from the economy range to the power range, thereby insuring a sufiicient supply of fuel to take care of or satisfy the condition which sometimes exists when the throttle valve is in a throttling position.

The carburetor herein illustrated is also designed so that when the throttle valve is in its wide open position, the supply of fuel to i": main passageway is not dependent entirely upon the suction that exists in said passageway at such times, but instead, the supply of fuel to the main passageway is obtained or effected by gravity or a siphon, thereby insuring a supply of suflicient fuel to take care of a heavy load that is imposed upon the engine when the throttle valve is in its wide open position, even though the air is flowing through the main passageway at such a low velocity as to produce a very slight suction on the fuel supplying device. As previously stated, one object of my present invention is to provide a novel means for destroying or breaking the siphon above referred to.

The carburetor comprises a main passageway A, a throttle valve B for controlling the flow of the combustible mixture to the intake of the engine, a fuel supplying device arranged in said main passageway between the inlet of same and the throttle valve and composed preferably of a nozzle C provided with a, fuel orifice 1 and a valve C for regulating the discharge of fuel from the orifice 1, a suction amplifier D arranged in the main passageway A in proximity to said fuel supplying device, an air admission valve E that is used to vary the admission of air to the main passageway and also used as a choke valve to facilitate the starting of the engine, a float chamber F to which liquid fuel is conducted by a suitable supply line, and a float G in the float chamber that actuates a valve H which governs the admission of the fuel to the float chamber from the supply line. The above described main elements or parts of the carburetor may be constructed in various ways without departing from the spirit of my invention, and if desired, the carburetor can be equipped with a flame arrester I arranged so as to snuff out a flame produced by back-firing of the engine.

Idle stabilizer In internal combustion engine carburetors of conventional design, if the operator fails to manually open the throttle valve in the event the suction in the intake of the engine drops below normal for any reason when the engine is idling, as, for example, due to the engine missing, the engine will stop, due to the fact that the suction in the intake is below normal, or, in other words, is not sufficient to draw in therequired amount of combustible mixture to maintain the engine in operation. In order to overcome this inherent defect of conventional carburetors, and thus eliminate the possibility of the engine stopping accidentally when it is idling, I have constructed my carburetor in such a way that if the suction in the intake of the engine drops or diminishes to a certain approximate or predetermined degree, when the engine is idling, thus resulting in a diminution in the supply of combustible mixture to the engine, a means will operate automatically to restore or resume the supply of combustible mixture to the engine. Such a means constitutes in effect an idle stabilizer, and while I have herein illustrated two different 'types or kinds of means for attaining the above described result, i. e., automatically maintaining the required supply of combustible mixture when the engine is idling, I wish it to be understood that my invention is not limited to a carburetor of the particular construction herein illustrated, as the idle stabilizer may be constructed in various other ways without departing from the spirit of my invention.

In the carburetor shown in Figure 3 the idle stabilizer just referred to is composed of a bypass around the throttle valve B, and a control valve J for said by-pass governed by the suction that exists in the main passageway between the throttle valve and the intake of the engine. Said by-pass is formed by a bore 2 in the side wall of the main passageway A provided, at its upper end with a port or opening 3 which communicates rescues with the main passageway at a point above the axis of movement of the throttle valve, and provided at its lower end with a port or opening 3 which communicates with said main passageway at a point below the axis of movement of the 8( throttle valve (see Figure 3). The control valve J for said by-pass consists of a plunger that is arranged vertically in a continuation of the bore in the side wall of the main passageway that com stitutes the by-pass above referred to. Said 8i plunger or control valve J is so constructed-and arranged that when the engine is idling with a closed throttle, the suction which then exists in the main passageway below the throttle valve will act on the control valve J and hold said valve in such a position that it closes the port 3 leading from the upper end of the by-pass. If, for any reason, said suction drops to a degree or point such that suflicient combustible mixture will not flow to the engine around the edge of the throttle 9- valve to maintain the engine in normal operation, the control valve J will move upwardly under the influence of an actuating spring 4, thus opening the port 3 in the upper end of the by-pass and causing the combustible mixture above the throttle valve to enter the by-pass and then escape from same through the port 3 into the main passageway at a point below the throttle valve. In this way the required supply of combustible mixture to the engine will be restored or resumed, automatically and'without any act on the part of the operator in charge of the engine. As soon as the normal or former suction in the intake of the engine is re-established, the control valve J will move downwardly, due to the 110 pull which said suction exerts on the lower end of same, thereby automatically cutting oil the flow of the combustible mixture from the main passageway into the by-pass around the throttle valve. When the carburetor is acting as a plain tube carburetor with the throttle valve and air admission valve in their wide open position, as shown in Figure 3, the control valve J of the idle stabilizer will, of course, be inactive.

, In Figures 8 and 9, I have illustrated another form of idle stabilizer that has all of the desir-. able features and characteristics of the idle stabilizer shown in Figure 3, but which is designed so as to overcome the necessity of forming a bore or other opening in the side wall of the main passageway A, so as to constitute a by-pass around the throttle valve. In the structure shown in Figures 8 and 9 the reference character A designates the main passageway of the conventional carburetor, B designates the throttle valve, 2 designates one or more ports in the throttle valve B and J designates a control valve or valves for the port or ports 2 formed preferably by a leaf spring attached to and arranged on that side of the throttle valve which is presented to the inlet end of the main passageway. The spring that constitutes said control valve J is of such tension that when the normal suction exists in the intake of the engine (enough suction to draw sufficient combustible mixture past the edge of the throttle valve to maintain the engine in operation), said suction will hold the control valve J' downwardly against the throttle valve,

as shown in full lines in Figure 9, and thus cause the port or ports 2 in the throttle valve to be closed. It said suction drops unduly, i. e., to such a degree that the required amount of combustible mixture will not be supplied to the engine through the annular space at the edge of the throttle valve B, the control valve J will flex in a direction to uncover the port or ports 2 in the throttlein engagement with the stop 10 on the rod K.

valve, as shown in broken lines in- Figure 9, whereupon the combustible mixture in the upper portion of the main passageway, above the throttle valve, will flow through the ports 2%, and thus reestablish the required flow of the combustible mixture to the engine. Thereafter, when the normal suction in the intake of the engine is re-established, the control valve J will flex in a direction to close the ports 2 and cut off the flow of the combustible mixture through said ports.

Air valve, choke and automatic choke relief The air admission valve E is combined with the throttle valve B in such a way that when'said throttle valve is moved from its closed towards its open position, the air admission valve E will be shifted automatically into a position to increase .the flow of air through the main passageway A, and likewise, when the throttle valve is moved from its open towards its closed position, the air admission valve E will be shifted automatically into a position to reduce the flow of air through the main passageway. Similarly, as hereinafter described, the fuel valve C which regulates the discharge of fuel from the orifice of the fuel nozzle C, moves in unison with the throttle valve to increase the supply of liquid fuel to the main passageway when the throttle valve is moved from its closed towards its open position and to reduce the supply of liquid fuel to the main passageway when the throttle valve is moved from its open towards its closed position. In the form of my invention herein illustrated the air admission valve E consists of a substantially diskshaped member arranged horizontally in the inlet portion of the main passageway A-and mounted so that it is capable of reciprocating longitudinally of said passageway towards and away from the inlet end of the venturi D which constitutes the suction amplifier of the carburetor. Said air admission valve is slidingly mounted on the exterior of the nozzle C, as shown in Figure 1, and said valve is providedwith an upwardly-projecting arm 5, from the upper end of which a horizontally-disposed plate 6 projects laterally, as shown in Figure 6. Said plate 6 has a hole in same that receives a stationary, vertically-disposed guide standard 7 that is used to retain the flame arrester I in position, and in view of the fact that the air valve E is slidingly mounted on the fuel nozzle, and the plate 6 attached to said valve is slidingly mounted on a guide standard 7 which is disposed parallel to the nozzle at one side of same, it is impossible for the air admission valve E to turn or rotate.

Various means may be employed to cause the air admission valve E and the fuel valve 0' to on the rod K below the plate 6 and arranged so as to exert upward pressure on the plate 6, and thus normally hold it against the stop 10 on the rod K (see Figures 2, 3 and 5) a When the throttle valve moves towards its open position, the rod K will move upwardly and the air valve E will also move upwardly, due, of course, to the fact that the spring 11 holds the plate 6 on the air valve When the throttle valve moves in the reverse direction, the rod K will move downwardly and the stop 10 on said rod, byco-operating with the plate 6, will move the air valve E downwardly or in a direction to reduce the flow of air through the main passageway. Such a construction also permits the air valve E to be moved independently of the throttle valve and without disturbing the position of the throttle valve, thereby making it possible to utilize the air valve E as a choke to cut off the flow of air through the venturi D during the operation of starting the engine. The movement of the air valve E independently of the throttle valve when said air valve is employed as a choke, is effected manually by the operator in charge of the engine, by means of a conventional Bowdin wire. The outer casing 12 of said Bowdin wire (see Figures 3 and 4) is rigidly attached to a stationary, vertically-disposed tube 13, and the operating member 14 of the Bowdin wire is rigidly attached to the upper end of a vertically-movable tube 15 that is reciprocatingly mounted on the stationary tube 13, the upper end of said operating member being attached by a set screw 16 to a transversely-disposed pin 17 that fits in a hole in the upper end of the tube 15. When the operator pulls the operating member 14 of the Bowdin wire outwardly, the tube 15 will move downwardly and the cross pin 17 at the upper end of said tube will engage the plate 6 at the upper end of the vertically-disposed arm on the air valve E, and thus move said air valve downwardly into engagement with the upper end or inlet end of the venturi D. As shown in Figure 3, said cross pin 17 is maintained in correct relationship with the plate 6 by means of a stationary guide 18 provided with a verticallydisposed, elongated slot 19 which receives one end of the pin 17. During the downward movement us ing member 14 of the Bowdin wire is moved in the 12 reverse direction, i. e., inwardly, the air valve E will be moved away from or out of engagement with the venturi D, by the expansive force of the spring 11, which tends to hold the plate 6 in engagement with the stop 10 on the rod K. As hereinafter explained, the movement of the air valve E into its choking position automatically increases the ratio of fuel to air, with the result that when the valve E is in its choking position, the nozzle C will supply a proportionately greater quantity of fuel to the main passageway A of the carburetor.

The suction amplifier or venturi D is mounted in such a way that it is capable of acting as an automatic choke relief that eliminates the possibility of the engine stopping in the event the operator fails to restore the air valve E or move it out of its choking position after the engine has started. In the case of a down-draft carburetor, as herein shown, the venturi D is mounted in the main passageway A in such a manner that it is capable of moving downwardly slightly, away from the air valve E, due to the suction which is created in the intake of the engine when the engine starts firing. The suction that is created in the intake of the engine when the engine is cranked manually orby an electrically-operated cranking device, is not suflicient to cause the venturi D to move away from the air valve E when said valve is in choking position, but

as soon as the engine starts firing, the suction in the intake causes the venturi D to move downwardly, due to the fact that the area of the -venturi D which is presented to the suction in the intake is considerably greater than the area of the air valve E that is presented to the suction in the intake. Normally, the venturi D is main.- tained in the position shown in. Figure 1 by means of an expansion spring 20 that acts upon the lower end of a plunger 21 mounted in a bore in the side wall of the main passageway A and provided with a laterally-projecting arm 22 that enters an annular groove 23 in the exterior of the venturi D. When the engine starts firing with the air valve E in its choking position, i. e., in engagement with the intake end of the venturi D, the suction in the intake overcomes the force of the spring 20 and causes the venturi D to move downwardly, thereby automatically admitting suflicient air to the main passageway, through the space between the air valve and the upper end of the venturi D, to eliminate the possibility of the engine dying or stalling, due to an insufficient supply of air for the charge of fuel that is drawn out of the fuel nozzle C. As soon as the operator restores the air valve E or moves it upwardly away from its choking position, the venturi D will be restored to its normal position by the spring 20. In the case of an updraft carburetor the venturi and air valve operate in practically the same manner, except that gravity is used to normally maintain the venturi in a certain position and the suction that is created in the intake when the engine starts firing causes the venturi to move upwardly away from the air valve.

Liquid ,fuel supply for nozzle The nozzle C receives its supply of liquid fuel from the float chamber F through a fuel duct which is so constructed and arranged that under certain operating conditions fuel is fed through said duct by gravity or by a siphoning action, under different operating conditions fuel is drawn through said duct by the suction produced inside of the nozzle C by the flow of air through the main passageway A, and under still different operating conditions the suction inside of the nozzle C, in addition to drawing fuel into the nozzle, is also utilized to retard the flow of the fuel from the float chamber F into said fuel duct. The said fuel duct may be constructed in various ways without departing from the spirit of my invention, but it will usually consist of a passageway leading to the interior of the fuel nozzle from the lower end portion of the float chamber F, and a means controlled by the fuel in the float chamber for establishing and cutting off communication between said duct and an air vented space in the upper portion of the float chamber, as hereinafter more fully described. In the carburetor herein illustrated the said fuel duct comprises a vertically-disposed fuel tube L arranged inside of the float chamber, as shown in Figure 1, with its lower end open and in close proximity to the bottom of said chamber and its upper end communicating with a passageway L that leads to the upper end of the interior of the nozzle C, a sleeve M of slightly greater internal diameter than the exterior of the fuel tube L arranged in concentric relation with same, and provided at its lower end with an inlet port or opening 24, and an air port 25 formed in the upper end portion of the sleeve M at a point high enough so that said air port 25 will always be located above the level of the fuel in the float chamber, said fuel level being designated bythe dot and dashline a: in Figure 1 The annular space between the fuel tube L and the sleeve M, and the air port 25, constitutes an air passageway that leads from an air vented space in the upper portion of the float chamber, and the fuel in the float chamber establishesor cuts off communication between said air passageway and the inte- 'rior of the fuel nozzle according to the suction that exists in the nozzle. The nozzle C is arranged in the main passageway A of the carburetor at such a point that the discharge orifice 1 of the nozzle 'is located below the normal fuel level a: of the float chamber F, and the suction amplifier or venturi D, inside of which the fuel nozzle is positioned, is made much larger than is the usual practice so as to insure the flow of a relatively great volume of air through the main passageway when the throttle valve is wide open. Such a suction amplifier is entirely Practical in my improved carburetor, because the suction in the main passageway A is not relied upon entirely to supply fuel to the main passageway when the throttle valve is in its wide open position. At such times gravity or a siphon is used to supply liquid fuel to the nozzle C, and hence, even though a heavy load is imposed on the engine when the throttle valve is in its wide open position, an adequate supply of fuel to the main passageway is assured.

When the carburetor is operating on the power range and acting as a plain tube carburetor with the throttle valve B and air admission valve E both wide open, fuel will be supplied to the discharge orifice 1 of the nozzle, due, of course, to the fact that said discharge orfice is lower than the fuel level of the float chamber. When the carburetor is operating on the economy range and acting as a mechanical carburetor with the throttlevalvewin a throttling position, fuel will be drawn through the fuel duct, formed by the fuel tube and passageway L by the suction created inside of said nozzle C by the air rushing through the main passageway. The hole 24 in the lower end of the sleeve M is made larger than the fuel discharge orifice 1 in the nozzle C, so as to not unduly restrict the-flow of fuel to the nozzle when the suction in the nozzle is low, and in order to prevent too much fuel from being supplied to the nozzle when the suction in the nozzle is at intermediate, the air port 25 in the upper end portion of the sleeve M is so proportioned that sufficient air from the upper portion of the float chamber will be drawn into the fuel tube L at intermediate suction to produce the correct ratio of fuel to air when the carburetor is operating on the economy range. At high suction on the economy range, the lower end of the fuel tube L a is not covered by fuel, and hence, the suction that exists in the nozzle is exerted directly on the upper portion of the float chamber, with the result that the escape of the fuel from the float chamber into the fuel tube L is retarded sufliciently to still maintain the correct ratio of ply of fuel for the nozzle and cannot possibly :30

come into action until after a certain approximate suction is created in the nozzle by the rush of air through the main passageway of the carburetor. This is desirable, in that the ratio of fuel to air progressively diminshes instead of progressively increases, when the carburetor is acting on the economy range, and it is desirable, in that it enables the carburetor to be designed so as to produce a prolonged accelerating charge, as hereinafter explained.

Various means may be usedto automatically vary the effective area of the discharge port 1 of the nozzle C according to the position of the throttle valve when the carburetor is operating on the economy range, and in the-carburetor herein shown the throttle valve'shaft 9 has attached to same a cam 26 which acts on the lower end of a vertically-disposed rod N provided at its upper end with a plate 2'7 which carries an element 28 (herein illustrated as a lever) provided with an adjusting screw 29 which is adapted to co-act with a head piece 30 on the upper end of the stem of the fuel valve C to vary or control the position of said fuel valve. Downward movement of the rod N and plate 27 causes the adjusting screw 29 in the element 28 to exert pressure on the stem of the fuel valve C in a direction to move said valve towards the fuel discharge orifice 1 which it controls, thereby diminishing the effective area of the port through which the fuel is supplied to the main passageway, and when the rod N and plate 27 move upwardly or in the reverse direction, the fuel valve C will move upwardly away from the discharge port 1, under the influence of an expansion spring 31 which acts on the head piece 30 attached to the upper end of the stem of the fuel valve. The cam 26 moves the rod N upwardly, when the throttle valve moves towards its open position, and when said throttle valve moves in the reverse direction, the rod N moves downwardly under the influence of a spring 32 whose lower end is attached to a stationary part of the carburetor, and whose up-' Siphon break and its adjustment After the flow of fuel upwardly through the fuel tube L and fuel passageway L into the nozzle has been established, fuel would continue to discharge from the orifice of the nozzle, even though the engine were stopped, due to the siphon formed by the nozzle, the passageway L and the fuel tube L. In order to automatically break said siphon and prevent the carburetor from being flooded when the engine is stopped, I form an air bleed or air admission port 33 in the extreme upper end portion of the fuel nozzle C (see Figure 1), and I govern said air bleed 33 by a control valve 0 which is combined with the fuel valve C in such a way that the control valve 0 will be unseated and the air bleed 33 will be opened in all positions of the throttle valve other than its wide open position. Consequently, whenever the engine is stopped, the siphon formed by the fuel nozzle, the fuel passageway 23 and the fuel tube L will be in direct communication with the atmosphere through the air bleed 33, owing to the fact that an internal combustion engine is invariably stopped with\ the throttle valve in a partly closed position. The control valve 0 for the air bleed 33 is herein illustrated as being formed on the stem of the fuel valve C, as shown in Figure 1. When the carburetor is acting as a plain tube carburetor with the throttle valve in its wide open position, the control valve 0 for the air bleed 33 will be held firmly seated, and thus prevent air from entering'the fuel nozzle by way of the air bleed 33.

As previously explained, liquid .fuel is supplied by gravity or by a siphonic action to the fuel nozzle C when the carburetor is acting as a plain tube carburetor with the throttle valve in its wide open position, and in order that the quantity of fuel supplied to the fuel nozzle at such times may be varied or regulated so as to obtain the correct ratio of fuel to air when the engine is operating at a very slow speed, means is provided for enabling the fuel level a: in the float chamber to be raised or lowered by manipulating an adjusting device. Said adjusting device is herein illustrated as consisting of an adjustable By turning the tubular member 35 in one direction the seat 34 of the float chamber valve H will be lowered, thereby causing the normal fuel level of the float chamber to rise, and by turning said tubular member in the opposite direction, the seat of the float chamber valve will be raised, thereby causing the normal fuel level of the float chamber to be lowered. A liquid-tight joint is produced between the tubular valve seat member 35 and the supporting part 36 'in which it is adjustably mounted, by means of an annular rib 37 on the exterior of said tubular member that fits tightly in a reamed bore in the supporting part 36.

Float chamber vent valve When an internal combustion engine is operating under a normal load with a partly closed throttle, and the load on the engine is suddenly increased, the engine tends to falter, due to the fact that the suction in the intake is not great enough to draw the required quantity of com-.

bustible mixture past the throttle valve. In order to overcome this inherent defect I have combined the control valve J of the idle stabilizer with a means that will automatically increase the fuel ratio whenever a sudden load is imposed on the engine when the carburetor is operating on the economy range with a partly closed throttle. Said means is herein illustrated as consisting of a vent valve P that varies the effective area of an air vent 38 in the top wall of the float chamber F, as shown in Figure 1. The vent valve P is of such design that when it is in one position, referred to for convenience as its closed position, there will be only a slight flow of air past said valve into the float chamber, and when said valve P is in its wide open position, as shown in full lines in Figure 1, there will be a free flow of air into the float chamber through the vent 38. Mechanism is provided for causing said vent valve P to move in a direction to increase the effective area of the air vent 38 whenever the control valve J of the idle stabilizer moves into a position to open the bypass around the throttle valve, and to move in a direction toreduce the effective area of the air vent 38 whenever the control valve of the idle stabilizer moves into a position to close the by-pass around the throttle valve. The mechanism that is used to produce such movements of the vent valve P consists of a rock lever B pivotally attached to the upper end of the control valve J of the' idle stabilizer and provided with an arm 39 to which the stem of the vent valve P is pivotally connected in any suitable way. When the control valve J of the idle stabilizer is functioning to close the by-pass around the throttle valve, the vent valve P will occupy its closed position shown in broken lines in Figure 1, and .there will only be a suflicient flow of air to the float chamber past said valve to vent the float chamber. As soon as the. control valve J of the idle stabilizer moves into position to open the by-pass around the throttle valve, as shown in Figure 3, the vent valve P will move into its wide open position, as shown in full lines in Figure 1, thus reducing the depression in the upper portion of the float chamber which previously had functioned to retard the flow of fuel from the float chamber into the fuel tube L. As previously explained, when the engine is operating under a normal load with a partly closed throttle, the suction that exists in the nozzle 0 is exerted on the fuel in the float chamber (through the air'bleed 25) in such a way as to retard the flow of fuel from the float chamber and prevent the nozzle from receiving too great a supply of fuel, it being understood that at such times the by-pass around the throttle valve is closed by the control valve J of-the idle stabilizer and that the vent valve P of the float chamber is in its closed position. Now, if a sudden load is imposed on the engine, the control valve J of the idle stabilizer will move into a position to open the bypass around the throttle valve, due to the drop in pressure in the intake of the engine, and the vent valveP of the float chamber will imme-.

diately open and thus destroy the suction in the upper portion of the float chamber that was acting to retard the escape of the fuel from the float chamber into the fuel tube L. Hence, as soon as the vent valve P opens a greater quantity of fuel will escape from the float chamber through the fuel tube L, with the result that the fuel ratio will be automatically increased to such an extent as to successfully take care of the additional load imposed upon the engine. It will thus be seen that under certain conditions when my improved carburetor is spenting on the economy range, a means becomes operative automatically to effect a change ever to the power range and to remain in this con dition, i. e., operating on the power range, so long as is necessary. As soon as the normal or former suction in the intake has been re-established, the control valve .J of the idle stabilizer will move automatically into a position to close the by-pass around the throttle valve and the' vent valve P will be restored to its closed position, thereby automatically re-establishingthe former fuel ratio by substantially reducing the admission of the air to the float chamber, and thus increasing the suction in the upper portion of said chamber that retards the escape of the fuel to the nozzle. When the engine is idling, the suction that exists in the fuel nozzle C is not exerted on the upper portion of the float chamber and does not act to retard the escape of the fuel from the float chamber into the fuel tube L, because at such times the fuel duct leading to the nozzle is cut off from the ai passageway to which the air bleed 25 leads, by a liquid seal formed by the fuel in the float chamber. Accordingly, the movement of the control valve J of the idle stabilizer into a position to open the by-pass around the throttle valve, when the engine is idling, has no affect on the fuel ratio, or, in other words, does not increase the supply of fuel to the nozzle, even though such movement of the controlvalve J causes the vent valve P to move into its wide open position, as previously explained. It is only when the engine is operating under a load, and the load is increased without a corresponding or simultaneous change in the position of the throttle valve, that the movement of the vent valve P into its open position automatically increases the fuel ratio.

Automatic increase of fuel ratio during choking operation The by-pass of the idle stabilizer is also used to insure a free flow of mixture into the intake of the engine during the operation of starting the engine, and the movement of the choking mechanism is used to effect a change in the position of the fuel valve 0', and thus increase the.

fuel ration during the startingoperation. These results are atttained by the use of a means that will mechanically open the control valve J of the idle stabilizer, and a means that will mechanically move the fuel valve C in a direction to increase the effective area of the fuel discharge port 1 of the nozzle whenever the operator pulls out the operating member 14 of the Bowdin wire to choke the engine. As shown in Figure 3, the rock lever R that is attached to the upper end of the control valve J, is provided with an upwardlyprojecting arm 40 whose upper end is inclined or beveled at 40*. When the valve J occupies such a position as to close the by-pass around the throttle valve, the inclined upper end 40 of the arm 40 is in the path of movement of the pin 17 on the movable tube 15 of the choking mechanism.

Accordingly, when the pin 17 moves downwardly,

due to an outward pull exerted on the operating member 14 of the Bowdin wire, said pin will coact with the inclined surface 40 of the arm 40 to swing said arm to the right, thereby imparting movement to the rock lever R in a direction to move the valve J upwardly so as to open the bypass around the throttle valve. llhe means that is used to mechanically open the fuel valve C during the starting operation consists of a lever S rockably mounted on the plate 2'7 carried by the vertically-movable rod N, previously described, and provided at its free end with an elongated slot 41 that receives the pin 17 carried by the movable tube 15 of the choking mechanism. The element or lever 28, previously mentioned, that carries the adjusting screw 29 which acts on the head piece at the upper end of the stem of the fuel valve C, is pivotally connected at 42 to the plate 27, and the right hand end of said lever 28 is provided with a pin 43 (see Figures 2 and 3) that enters a hole in a block 44 which is attached to the lever S adjacent its axis of movement, or, in other words, adjacent to the point Where said lever S is pivotally connected to the plate 2'7. Accordingly, if the free end or left hand end of the lever S moves downwardly, the left hand end 145 of the lever 28 will move upwardly, with the result that the adjusting screw 29 in the lever 28 will move in a direction to permit the fuel valve C to move upwardly, and thus increase the effective area of the discharge port 1 of the fuel noz- 150 zle. It will thus be seen that when the operating member 14 of the Bowdin wire is pulled outwardly to choke the engine, the pin 17, by co-acting with the lever S, will move the lever 28 in a direction to cause the fuel nozzle to supply a proportionately greater quantity, of fuel. As soon as the operating member 14 of the Bowdin wire is restored or pushed inwardly, the normal position of the lever 28, relatively to the plate 27 which carries it, will be re-established and the fuel valve C will be moved downwardly so as to diminish the effective area of the discharge port 1 of the fuel nozzle. I

' Acceleration moved suddenly towards its open position, a

stream of raw fuel will flow through the fuel duct leading to the nozzle during the first portion of the accelerating period and then air will start to break into said duct and diminish the accelerating charge. In the particular form of my invention herein illustrated an accelerating movement of the throttle valve causes raw fuel to flow upwardly through the fuel tube L and continue to flow until the lower end of the fuel tube L becomes uncovered, whereupon air in the upper portion of the float chamber will escape through the air bleed 25, and thence flow through the fuel duct formed by the fuel tube L and the passageway L which leads from the upper end of said fuel tube to the nozzle. Due to the fact that the air stream, which is relied upon to diminish the accelerating charge (the air which escapes from the upper end ofthe float chamber through the air bleed 25) cannot come into action until after .a considerable quantity of raw fuel has been drawn into the nozzle, a rich charge of fuel is insured during the first portion of the accelerating operation when it is most needed. Moreover, such a structure eliminates the possibility of the air stream coming into action too soon, as it is impossible for air to be drawn into the nozzle through the air bleed 25 until after the fuel that serves as a liquid seal for the fuel tube L has been consumed or drawn into the nozzle, attention being called to the fact that the air stream relied upon to control the accelerating charge enters the nozzle through the same duct or passageway that the raw fuel is supplied to the nozzle; Another advantage 'or desirable feature of such a construction is that it can be designed so as to obtain an accelerating charge of any desired duration. If a quick accelerating charge or a charge of short duration is desired, the air bleed 25 leading from the upper end of the float chamber and the air vent 38 are made relatively large, whereby the pressures will be balanced quickly, Whereas, if an accelerating charge of prolonged duration is desired, the size of the air bleed 25 and the air vent 38 can be reduced, with the result that a long period will be required to balance the pressures inside of and outside of the float chamber while drawing the accelerating charge into the nozzle.

choke the engine, said amplifier being so mount- In other words, the relation of the vent 38 to the air bleed 25 determines the balancing pressure in the float chamber; to increase the amount of the acceleration charge the air bleed is calibrated so as to produce a high balancing pressure, and to reduce or lessen the acceleration charge, said air bleed is calibrated so as to produce a low balancing pressure.

Having thus described my invention, what I desire to claim and secure by Letters Patent is:

1. In a carburetor, the combination of a normally open main passageway, a suction amplifier in said passageway, and an air admission valve adapted to vbe moved against said amplifier to ed that the suction in the intake when the engine starts firing will automatically move said amplifier away from said valve for the purpose described.

2. In a plain tube carburetor, the combination of a main passageway, a suction amplifier mounted in said passageway so as to be capable of moving longitudinally of same, and a choke valve that is adapted to be moved towards said amplifier to cut off the fiow of air through the main passageway, the area of said amplifier that is presented to the suction in the intake being great enough to cause said amplifier to move automatically away from the choke valve so as to admit air to the intake, when the engine starts firing.

3. In a plain tube carburetor, the combination of a main passageway, a movable venturi in said passageway, means for normally holding said venturi in a certain approximate position, and an air admission valve adapted to be moved into engagement with the intake end of the venturi to choke the engine, said venturi having a greater internal area than the area of said valve that is presented to the suction in the intake during choking for opposing said means. i

4. A carburetor provided with a fuel delivery device, a fuel supply duct for said delivery device, constructed so that. fuel will be discharged from said delivery device by a siphonic action under open throttle condLtions, a valve for admitting air to said duct so as to destroy the siphonic action when the engine is stopped, and a manually-operated means for insuring that said valve will function when the throttle is closed.

5. A carburetor provided with a siphon for deliverlng fuel to the main passageway of the carburetor under open throttle conditions, and a means for breaking said siphon, operatively connected with the throttle valve of the carburetor under closed throttle conditions.

6. A carburetor, comprising a fuel delivery device, a duct adapted to supply fuel to said device by a siphonic action under certain conditions, a fuel valve for regulating the discharge of fuel from said delivery device operatively connected with the throttle valve, and means governed by said fuel valve for admitting air to the fuel duct leading to the delivery device whenever the throttle valve is in a position other than its substantially fully open position. I

7. A carburetor provided with a main passageway, a float chamber, a fuel delivery device in said main passageway having a discharge orifice located at a point lower than the normal fuel level of the float chamber, an adjustable means for varying the fuel level of the float chamber, a fuel duct leading from the float chamber to said delivery device and constructed so that under certain conditions fuel will siphon out of said deliv- 150 ery device, and means governed by the throttle valve for establishing atmospheric pressure in said fuel duct when the engine is stopped and the throttle valve is in other than its substantially fully open position.

8. In a carburetor, a main passageway, a float chamber, a float operated valve for admitting fuel to said chamber from a source of supply, an adjustable seat for said valve that isadapted to be moved to vary the normal fuel level of the float chamber, a siphon for delivering fuel to the main passageway from said float chamber, and means for admitting air to said siphon when the engine is stopped, so as to destroy the siphonic action.

9. A carburetor provided with a main passageway, a float chamber, a fuel delivery device in said main passageway connected with the float chamber by a fuel supply duct, a means controlled by the fuel in the float chamber for establishing com- .munication between said supply duct and the upper portion of the float chamber whereby the suction in the nozzle will be utilized to exert a retarding action on the escape of the fuel from the float chamber, and a means governed by the suction in the intake of the engine below or beyond the throttle valve, for automatically reducing the pressure in the upper portion of the float chamber under certain conditions.

10. A carburetor provided with a main passage way, a fuel delivery device in said passageway, a float chamber, a supply duct leading from said float chamber to said delivery device, means controlled by the level of the fuel in the float chamber for. establishing communication between said duct and the upper portion of the float chamber under certain conditions, a vent valve for the float cham-' ber, and a means governed by the suction in the intake of the engine below or beyond the throttle valve for effecting a change in the position of said vent valve.

l1. A carburetor provided with a main passageway, a float chamber,a fuel delivery device in said main passageway, a throttle valve for said main passageway, a by-pass around the throttle valve, a vent valve for the float chamber, a control valve for saidby-pass operatively connected with said vent valve and arranged so that a certain approximate suction in the intake holds said control valve in a position to closethe by-pass, a supplyduct leading from the float chamber to said delivery device, and a means for admitting air to said duct from the upper portion of the float chamber under certain conditions.

12. A carburetor provided with a main passageway, a fuel delivery. device in said passageway, a throttle valve for said passageway, a by-pass around said throttle valve, a control valve for said by-pass, a choke valve for said main passageway, air-controlled, automatic acting accelerating means, and means for opening said by-pass valve when the choke valve is moved into its operative or closed position.

13. A carburetor provided with a main passage- 14. A carburetor provided with a main passageway, a fuel delivery device in said passageway, a throttle valve for said passageway, a bypass around said throttle valve, a control valve for said by-pass, a choke valve for said main passageway, and means for opening said by-pass valve when the choke valve is moved into its operative or closed position.

15. A carburetor provided with a main passageway, a fuel delivery device in said passageway, a throttle valve for said passageway, a by-pass around said throttle valve, a control valve for said by-pass, a choke valve for said main passageway, and mechanism for opening the control valve of the by-pass and changing the fuel ratio of said delivery device when said choke valve is rendered operative or moved into its closed position. 

